There are several different kinds of certainty. One kind relates more to perceptions of basic facts, another important kind relates to the degree of justification you have for a belief (which must be carefully distinguished from the evidence you have for a belief - evidence relating to probability, and things like that, rather than certainty).

In On Certainty Wittgenstein says we sometimes forget about cases where we're certain, then turn out to be wrong. That actually highlights the function of the second kind of certainty in a way.

Basically the second kind of certainty is contextual and has to do with the degree to which we've dotted our "i"s and crossed our "t"s - it relates to coherence and the way our proposition or theory fits in with (what we accept so far to be) a base of established knowledge, not contradicting it. Here, new knowledge is the only thing that can overturn certainty.

Uncertainty, for the first (perceptual certainty) sense, would be where for one reason or another you're not sure whether you saw a thing right (perhaps the conditions make you doubt); in the second sense, it would be where there are gaps in your argument for the coherence of what you're saying with the established knowledge base (e.g. there are some possible calculations you've left out because you didn't have time, or some relevant piece of information, etc.).

Certainty in the second sense is absolute (relative to the totality of the knowledge base) because it's simply a matter of logical coherence, it's not a question of degree. It's probably rather confusing and bad practice to assimilate evidential probability approaching 1 to certainty, although the practice seems to be deeply rooted now.

In the most general sense, you are uncertain where there's reason to doubt.

Uncertainty has no structure. It is the unavoidable consequence of reality imposing itself upon one's thought/belief system in such a way that s/he has no choice but to realize that what they believed to be true(to be the case), is not. Certainty and it's counterpart uncertainty - at their core - are based upon and/or directly involve trust and truth. Guru talked of kinds of certainty/uncertainty...

Being uncertain of observation is nothing more than losing trust in(doubting the dependability of) one's own physiological sensory perception and/or accompanying critical thinking skills, and vice-versa. Being uncertain of 'X' is being uncertain of the truth of 'X', and vice-versa.

How can we model it? How do we divide it up? How do we understand it as a thing in and of itself?

Hi VoT!

I remember the times when (I was new here) you was a higher (and more sure) philosopher than me (what is to say very high )! But I am somewhat deceived in reading this: How do we understand it as a thing in and of itself?

-Nobody does, and not even cares, since it is a "thing in itself" and moreover "outside itself" are contradictions in terms. From that assumption forbidding such a basic thing as a definition, we were lead to any improbable and worthless thing.

-But even your first question is void. (In very general terms), since a structure means a model, and since a model - being what it is - is never (even partially) false - (because of the definition of false, which is what canNOT be assimilated), then uncertainty - which stand for unknown either if it stands for Heisenberg principle or any other notion deriving from the unknown - so I answer you, being 100% sure of this, that uncertainty has not a sole structure.

-The only question which seems to mean a few, even if this seems strange, is: "How do we divide it".

Let's consider the entropy, as it is the nearest concept I think to know a little about; entropy is measured in J/K (joules per kelvins). That is why some of the physicists talk to us about "energy efficiency" for it.

If you take differences (no modification to the kelvins, since they are a measure from absolute zero), then if you invest 1 J at 0 K, you'll get a high temperature increase, and a rapid one. But if you invest 1 J at 373 K, the temperature increase will be lower as well as slower.

The last consideration is really from basic school in such, but that is all I found to answer to you. That written, I even wonder, sometimes, if this division makes sense; since K are for an absolute temperature, and J for relative energy addition, I am near to consider that this division is either nonsense, or at the contrary an evidence; (in few word, that does not tell us very deeply).

The structure of uncertainly involves a) the acceptance that none of us can ever know everything about anything, b) words are not the reality they describe so no verbal formulations can be completely accurate because they are never the truth itself, c) the actual territory or 'reality' keeps changing so our fixed verbal assertions will not remain completely accurate or true for all time, nor for everyone, d) we remain susceptible to errors in judgement as long as we live and breathe. Plus, as we grow, change, and hopefully mature, the same 'facts' can look different to us and we can learn to interpret them differently, and describe them differently, or find different facets of them far more important than some others we used to find more important.

We can never know everything about even one single 'thing'. On top of that, everything is ultimately related to everything else, so to fully know everything about one thing you would eventually have to know everything about everything.

I remember being in a meeting with a table full of computer analysts and programmers—ostensibly some of the most intelligent people around—most having advanced college degrees. One project manager made a statement that, to me, was as clear as the fact that we were sitting at a table and our butts were in chairs. Nobody else at the table understood her point. I felt very confident, almost certain, because what she had pointed out was so obvious and important to me, that I could quickly explain her insight to the group in a way they could understand it.

After two 'concisely eloquent' attempts, in my humble opinion, I gave up. They could not see our point! It was blatantly obvious to us and invisible to everyone else at the table. She asked me after the meeting if she was crazy or did what she say make obvious sense. When I assured her it made obvious sense to me, she looked quite relieved.

I believe their past experiences as a development team may have traumatized them into ignoring certain types of actions as politically dangerous so they were psychologically 'refusing' to see what she was saying. Her suggestion triggered them to re-experience a past ordeal as if it were happening in the current instant. They were reliving the past. She and I had worked on many different software development projects while they had worked together in the same department on the same projects with the same managers for a number of years. They were 'certain' what we were saying made no sense and would be a foolish, useless or even destructively stupid thing to do. They were confidently, passionately certain.

Time proved us right and their lead analyst later admitted, privately, he should have listened to me. It was clear from his attitude as he said it, though, that he still didn't clearly understand what we had been suggesting nor why we had been suggesting it and certainly not how to go about achieving it. He didn't have the intuitive reflexes borne of experience to appreciate our frames of reference no matter how simple and obvious they appeared to me. For all his years as an analyst this was the first project he had ever managed and he apparently hadn't developed an appropriate mindset from which to evaluate and develop strategic plans.

These are just a few brief glimpses of 'the structure of uncertainty'.